This invention relates to improved high current cell shorting switches. The switches are particularly applicable in chlorine production plants where large amounts of current are utilized. These plants often contain as many as 200 chlorine producing cells connected in series, each of which may contain as many as 20 power grids.
Normally, the voltage across each cell is comparatively low thus leaving the output of the cell directly proportional to the operating current. Currents in excess of 8,000 amperes are not unusual.
When it becomes necessary to service one of the cells it would be highly undesirable to shut down the entire line. To solve this problem, it is known to insert a switch or switches across the terminals of the defective cell thus providing a shunt circuit in the series system and enabling the cell to be serviced.
As noted above, each cell might contain as many as 20 power grids, thereby necessitating the use of 20 shorting switches for each cell. A representative plant might then typically have as many as 2,000 shorting switches installed at any one time.
Because of the large currents which pass through the system and the switch contacts it has been found desirable to connect a multiplicity of contacts in parallel. The problem which arises however is that provision must be made for self-alignment and effective simultaneous engagement and disengagement of the contacts.
Moreover, because of the relatively high magnitudes of current carried by the shorting switches, the contact surfaces have a tendency to burn and corrode. This tendency is greatly accelerated if the contacts do not engage simultaneously and/or if the contacts make only point or line contact over a relatively small area.
The problem therefore is to provide a switch which makes highly effective contact over a large area and which can be easily repaired after contact elements degenerate over a period of time. Naturally, since an entire cell must be shut down during any repair, rapid repair or replacement of defective switch contacts is highly advantageous. In the past this has proven to be a substantial problem since repair of the switches has necessitated the removal of them from the installation. These switches can weigh in excess of 100 pounds and are often mounted such that repairmen must work from below the switch installation. This has normally been a two-man repair operation.
Further, upon removal of damaged switches, it is often essential to replace larger copper bus bars which have worn contact surfaces.
It is the object of this invention to obviate the problems of labor, material, and shut down costs attendant the need for refurbishing of high current cell shorting switches.